In the conventional art, various compressors for compressing a compressible medium such as the refrigerant of a freezer have been proposed, and, among these, the single screw compressor is known to feature little vibration, low noise, and high reliability.
A single screw compressor according to Japanese Unexamined Patent Application Publication No. 2002-202080 comprises: a cylindrically shaped screw rotor, the outer circumferential surface of which has a plurality of helical grooves; at least one gate rotor, which rotates while meshing with the screw rotor; and a casing, which houses the screw rotor. The compressible medium, such as a refrigerant, is fed to the helical grooves of the screw rotor, which rotates inside the casing, is compressed inside a space defined by the helical grooves, teeth of the gate rotor, and the casing, and is discharged from a discharge port of the casing.
In addition, a single screw compressor according to U.S. Reissue Pat. No. 30400 comprises: a tapered or a reverse tapered screw rotor, the outer diameter of which changes from an inlet side to a discharge side; and a pinion, which rotates while meshing with the helical grooves of the screw rotor. In the single screw compressor according to the U.S. Reissue Pat. No. 30400 as well, the compressible medium, such as the refrigerant, is fed to the helical grooves of the screw rotor rotating inside the casing, is compressed inside a space defined by the helical grooves, the teeth of the pinion, and the casing and is discharged from a discharge port of the casing.